Reclosing circuit interrupter



. 2 Sheets-Sheet Filed July l0. 1931 f prior to the sixth rebfosure, it is usually a Patented Mar. 14, 1933A y UNITED STATES PATENT OFFICE'.v

FORI) W. HARRIS, 0F LOS ANGELES, CALIFORNIA, ASSIGNOR T0 PATCO,INC., OF LOS ANGELES, CALIFORNIA, A CORPORATION-OF CALIFORNIA RECLOSING CIRCUIT -INTERRUPTER Application led July 10,

lthe interrupterupon the occurrence of an.

overload, but is also provided with means for automatically:l reclosing `the interrupter within a short but usually definite s eriod `after it has opened so that-if the con itions producing the overload have ceased, the circuit will be automatically restored to normal operation. If the overload persists upon reclosing the interru ter, the interrupter immediately reopens. uch reclosing interrupters are often arranged to close a plurality of times but it is necessary fortheir successful operation that the number of reclosures belimited since it sometimes happens due to line failure or other causes that the condi'- tion causing the overload persists and does 3b Many overloads caused nby swinging wires or other transient conditions do not recur upon reclosing the interrupter either the first or )some subsequent time, in which event no per-4 manent discontinuance of electric service refsults since the interrupter remains closed 1 lvafter the transient condition disappears. It

is'ffound in practice that the number'of reclosuresneed not be very great, six reclosures 1. 11 beingcommonly required, since if the condiftion causing the overl ad does not disappear gconditionof suicient permanence to require the attention of the lineman and one that y makesrfurter `attempts to operate the'line extremely dangerous and usually futile. My

invention is well ladapted to provideexactly the sort of service required in a reclosing in'- terrupter. Y @Previous inventors have constructed inter- `not disappear when the circuit isopened.

rupters that-would provide for reclosuresV 1931. Serial No.v 549,829.

in a position t0 again reclose the interrupter the predetermined number of times, just as if the interrupter had not previously opened.

One of the principal purposes of using rey closing interrupters is to keep the lines in service where. a swinging wire or other transient condition occurs; It sometimes happens, however, that this condition recurs at lntervals of one hour or more over long'periods, during which periods the interrupter opens frequently but never remains Open. This may result in a defective line being kept in service when it should be repaired. This defect in the operation of the ordinary reclosing interrupter is due to the fact that it entirely resets (or resumes its initial condition) after theinterrupter hasremained closed for a a few minutes after it has opened once or more in response to unfavorable transient conditions and thatonce entirely reset, it then functions without regard to any condition which has preceded the resetting. l

It is an object of my invention to provide a reclosing interrupter which for a long period after` any successful reclosing, if reopened by .a recurrence of the unfavorable transient condition, will then be influenced 1n its further operation by conditions occurring prior 'to the successful reclosing. For

example, a standard type of reclosing interrupter may be setto reclose six times and then remain open if the unfavorable conditioir of 'the circuit persists. If it remains closed upon any of said six reclosures for a periodof say two minutes, it resets; `that is, it adjusts itself so that it will again reclose six times. As a result, if an-unfavorable condition, such as a swinging Wire, exists on the circuit which'recurs vat intervals of three minutes, e interrupter will open and close every three minutes indefinitely. By my invention/it is possible -to provide a reclosing -interriipte'r which if. it opens upon the occurrenceofan `unfavorable condition Aas often 1 ias six times in a week, it will then stay open. Such long time periods are not usually necessary however, and if the reclosing mechanism has means allowing it to reclose not more than once an hour, it meets operating conditions.

I n my invention the effects of several openings are cumulative. For example, if the interrupter is so constructed as to open six times upon a persistent unfavorable condition and it stays closed after having opened five times, it will reopen and stay open after an interval of several minutes if the condition again persists long enough to open the interrupter twice, and will be operative over even a longer interval if the condition per'- sists long enough to open the interrupter three or more times.

All this I accomplish by using a thermal relay which stores -heat during the time the interrupter is open, the amount of heat so stored depending upon the number of times the interrupter opens, this heat being dissipated slowly after the interrupter finally remains .closed so that additional openingsof the interrupter, even after a considerable time interval, add heat tothe supply of heat remaining from the original storage so that the interrupter will stay open after a smallernumber of reclosures than it would if a longer time had elapsed since its prior reclosure.

Further objects -and advantages will be made evident hereinafter.

In the drawings, which illustrate one form of thermal relay and one application of that relay:

Fig. 1 is a front elevation of the relay;

Fig. 2 is a section through the thermal storage portion thereof Fig. 3 is a side elevation;

Fig. 4 is a diagram of connections of the relay applied to a conventional circuit interrupter.

The thermal relay shown in Figs. 1, 2, and 3 includes a thermal storage element 10\P The element 10 consists of a coil of wire 11 wound on thin mica 12 over a metal tube 13 (having a closed lower end), the wire 11 having terminals 14. The 4wire 11 is covered with heat insulation 15.` Inside the tube 13 is a body of low melting alloy 16. A^lloys having melting points below 200o F. are available (and quite suitable)V for this purpose. Projecting into the tube 13 and normally embedded 'and rigidly locked in the body of alloy 16 (when the alloy is cold) is a plunger 17. The plunger '17 is lrigidly,

locked to'a cross-bar 18 which is secured to the upper ends of two slide rods 19:) The slide rods 19 pass loosely through holes in two supports 20 which support the tube 13 and which are themselves supported on a slate or other insulating panel 21.

F Carried on the lower end of the slide rods 19 is a cross-bar 22 of hard rubber or other insulating material. Carried on the crossbar 22 and movable therewith are two fingers 23 preferably formed of spring brass (or bronze), each of these fingers being connected to a post 24 fixed on the panel 21 through a fiexible copper cable 25 so that the cross-bar 22 can move up and down over a limited path without disconnecting the fingers 23 from the posts 24.l

VThe plunger 17 and the above described 31 whenever an electric current of sufficient Y strength is passed through the coil.

Projecting through the upper head 30 is a stem 33 which is rigidly secured to and moves withy the core 32. Carried on but insulated from lthe stem 33 is a reset disc 34 which is so placed and spaced that it makes contact with both the fingers-23 when the fingers drop due to the melting of the alloy 16 or when it is moved upwardly due to the movement of the core 32. The end of the stern projects above the disc 34 a sufiicient distance to strike the cross-bar 22 after good electrical contact is made between the fingers 23 and the disc 34. Insulated from and carried .by the core 32 is'a main thermal relay disc 35 which in its lowerposition makes electrical contact with bronze fingers 36 carried on posts 37 set in the panel 21. `When the coil 31 is energized and the core 32 is pulled up thereby, this contact is' broken due to the disc 35 being lifted from the fingers 36. V The thermal relay above described is intended to break the circuit through the iingers 36 Whenever a definite quantity of electricity measured in watt seconds, for example, has flowedthrough the wire 11. This is accomplished by connecting one terminal 40 of the coil 31 through apost 24 and a flexible cable 25 to a fingerf23, the other terminal 41 of the coil being connected to one lterminal of a battery 42 which is connected through a wire 43 to the other post 24 and through the other flexible cable 25 to the other finger 23. When so 'connected the thermal relay operates as follows.

The parts being in the position shown, in the drawings, current is passed through the wire 11. This wire isl preferably, vbut i not necessarily, a wire such as those used in heating appliances which have a small increase in resistance as they increase in temperature and which are highly resistant to oxidation or corrosion. Due to the electrical resistance of this wire, heat is developed therein which iiows through the mica 12 and the tube 13 to the alloy 16, which is therefore gradually heated during the time current passes `through the wire 11. It is to be noted that the quantity of heat so delivered to and stored in the alloy 16 is proportional to the wattage of the current flowing in the wire 11. As heat is stored in the alloy 16, the temperature of the alloy is increased gradually to the melting point. The time required to reach this temperature is calledthe time element of the relay. By suitably proportioning the famount of alloy 16 an the resistance of the wire 11, almost any desired time element may be obtained.

As soon as the alloy is melted sufficiently to l allow the plunger 17 to fall freely, the plunger and parts connected thereto fall and the lingers 23 make contact withthe disc 34, completing/the circuit fromI the battery 42' stem 33 topush upwardly on the bar 22 and V push-'the lunger 17 back into its initial position, the ngers 23 maintaining their Contact with the. disc 34 so that the coil 31`remains energized throughout this movement and after it is completed. As the core 32 moves upwardly, it lifts the disc 35. If desired, this upward movement of the disc 35 can be used to open thecircuit through the wire 11 by connecting one of the terminals 14 through a wire 44 with one of the fingers 36, the other linger 36 'and the other terminal 14 being connected to the circuit feeding the wire.

vAfter the core 32 has moved up and the plunger 17 is restored to its upper position,

currentwill therefore be cut off from thel wire 11 and no more heat will be delivered to the alloy 16, which will start to cool. The

rate of cooling is determined by the characf.

teristics of the heat insulation 15. If a very slow rate of cooling is desired, the entire thermal storage element can be enclosed in a vacuum bottle. Such an extremely slow cooling rate is not necessary, however, for most uses to which the relay is put and ordinary asbestos paper wound around the wire 11 is suliicient to supply the necessary heat insulation Y15. Whatever the rate of cool ing, the alloy will eventually cool and solidity, again locking the plunger in the position shown in the drawin s. If now the circuit through the coil 31 1s opened, the, core 32 drops and the relay-parts are all in the initial position shown in the drawing, in which position the disc 35 rests on the fingers 36 and the wire 11 may be again energized.

The vabove-described relay therefore opensv the circuit between the fingers 36 whenever a definite-amount or watt. seconds of vener in the form of heat has been delivered to- 7e alloy 16, or when a definite vamount of energy current flowing in the wire 11 has a constantY value or a constant average value, in the case of an alternating or pulsating current, the

circuit will be broken at the fingers 36 acerlain definite time after the current starts to The principal value of the relay resides in itsl integrating characteristics. If the current flowing inthe wie- 11 is intermittent or irregular in value, the wire 11 automatically integrates the energy values of this current s'o that the relay is responsive to the average energy flowing through the wire 11 during any period.

It should be noted that the relay is also fully operative if for any reason the plunger 17 is locked in its lower position at the beginning of the operative cycle, since in this psition the core 32 is held in its lower position against the pull of the coil 31 and the circuit between the fingers 36 cannot be broken until the alloy 16 melts and allovvs the plunger 17 to rise. The relay" thus does not open the i which is closed to close the circuit interrupter by a closing coil 104.

In the diagram I have shown a circuit invvterrupter which is closed by a solenoid.

Many circuit interrupters are closed by motor operated mechanlsms and my invention is equally applicable to motor operated circuit interrupters, the closing coil shown and other electrically energizedV means for actuating the contacts being generally included- -in the term electrically energized Iactuators. Moreover, many circuit interrupters to which my invention is applicable areghydraulically, pneumatically, -or mechanically energized by various forms of force applying devices generally included in Athe broader term actuators.

.The interrupter is opened by` a trip coil 105 acting on the toggle 103. If'the `closing coil 104 is energized, the interrupter is closed and lif the trip coil 105 is energized, the interrupter is opened.

A pilot switch 106 is provided having a movable contact 107 which moves with the main contacts of the interrupter, closing a circuit between contacts 108 in its upper position and between contacts 109 inits lower position. Y

The above parts 101 to 109 inclusive constitute an electrically operated circuit interrupter which is standard in the art and therefore shown diagrammatically. Other wellknowir forms of circuit interrupters may be substituted therefor without departing from the spirit of my invention.

The circuit interrupter may be caused to open upon the occurrence of any abnormal circuit condition in the circuit 102 by any well known means such as an overload relay 110 having a coil 111 connected to the secondaryy 112 of a series transformer 113 whose primary 114 `is connected into the distribu tion circuit 102. The relay 110 is provided with two contacts 115 which are electrically connected to each other by a movable bridging member 116 whenever the current in the circuit 102 exceeds a predetermined value. Other types of relay or tripping devices may be used without departing from the spirit of my invention.

It is desirable that the interrupter should -not close immediately upon being opened, a

short dead interval so that any free arcs or insulator flash-overs which may have caused the previous overload or short circuit ,interval .of thirty seconds is generally considered long ,enough for this purpose although this should not be regarded as 'a delinite and invariable practice, much longer times being perfectly practical. Some types of circuit interrupters, notably spring actuated devices in which the spring is com-v pressed by a small motor, require asuiciently. long interval for their operation, but the usual solenoid operatedinterrupter will reclose very quickly. If it is desired to delay the reclosing of the interrupter for a longer period than is inherent to the interrupter mechanism, a time limit relay is used.

' My thermal relay is well vadapted for use as a time. limit relay and can, be soiused but for simplicity in the diagram (Fig. 4) I have shown a time limit relay 120 having an actuating coil 121 which acts upon a core 122 to pull it upwardly "when the coil 121 is energized. The core 122 carries a bridging member 123 which makes electrical contact between contacts 124 just before it reaches its upper position. A dash-pot 125 retards the upward movement of thecore 122"'to produce the desired time interval. The dash.

' lpot is preferably so"constructed that it is les.

duction relays which performs the same funcf.

tion, `and which closesan electric circuit at relay is itself energized. The solenoid relay lends itself better to diagrammatic representation and is therefore shown.

In addition to the automatic reclosing mechanism, it iskof course, necessary to provide means by which an operator can manually control the opening and closing of the interrupter. For this purpose I provide a manual control switch 130 having a movable arm 131 pivoted at 132 and normally held by springs in contact with a central contact 133, but which is so arranged that it can. be moved (and held) by hand to make contact with a contact 134 if it is desired to close the interrupter, or to make -contact with a contact 135 if it is desired to open the interrupter, the arm 131 snappine back into its central position whenever the hand is removed. If desired,`lorcking means may be provided for locking the manual control switch in either theA opening or closing position.

Some source yof electrical energy must be provided for actuating the various apparatus .above described and l have shown a battery 140 as a convenient source, without, ofcourse, intending to, limit myself to a battery, since various other sources may be used, or, if the apparatus is suitably designed, it can be energized from the source of energy feeding the circuit `102.

the end of a definite time interval after the In the diagram (Fig. 4) the parts are l shown in the position they assume in normal position i that is, with the circuit interrupter closed and a normal load on the circuit 102. Ifnow an overload occurs, the movable member 116 of the overload relay is lifted and electrical connection is made thereby between the contacts 115. This closes a trip circuit through the trip coil through wires `200, 201, 202 203, 204, 205, and 206 and the battery 140. Note that the contacts 108 of the pilot switch 106 are bridged. by the member`107 and are in this circuit.

This energization of the trip coil causes the circuit to open the pilot switch 106, then opening the trip circuit, thus cutting oli' current from the trip coil 105.

The opening of the circuit causes themember 107 of the pilot switch 106 to bridge the contacts 109, and the coil 121., of the time element relay is energized through a time element circuit consisting of wires 210, 211, 212, and213, through fingers 36 and thermal relay disc 35, wires 221, and 215, through the movablearm 131 of the manual control switch 130, through the wires 216 and. 200,

the operation o f the time element relay 120,

At vthe time theinterrupterbpens, it starts 1'30 the wire 11 in the thermal relay being energized from the pilot switch 106 through a thermal relay circuit consisting of the lwires 210, 211, 220, 11,214, 213, 221,215,the arm 131, the wires 216 and 200, the battery 140, and wires 206 and 205 back to a contact 109 of the pilot switch. The wirel 11 then transmits energy to the alloy in the thermal switch as long as the thermal relay circuit is closed. Let us assume that the thermal relay is so constructed that the thermal relay circuit must be closed for a little less than three minutes to melt the alloy. Note that the fingers 36 are in the thermal relay circuit. The thermal relay will therefore not operate prior to the time the time limit relay (which is set to operate in thirty seconds) operates.

The time limit relay operates at the end of thirty seconds, closing a closing coil circuit passing through 124, this circuit consisting of the wires 230, 231 and 210, the lower contacts 109 of the pilot switch, the wires 205 and 206, the battery 140, the wires 200 and 216, the arm 131, the wires 215, 221, 213, and 232, back to a contact 124. This energizes the closing coil 104 which closes the interrupter. As the interrupter closes, the member 107 opens the circuit between the contacts 109 of the pilot switch 106, and opens the time element relay, the thermal relay, and the closing circuit. The member 123 of the time element relay therefore drops to its initial position as 'shown in Fig. 4 and current is cut off from the wire 11 of the thermal relay, which starts to cool slowly.

If during the thirty seconds the interrupter has been open the condition that caused the overload on the circuit 102 to occur has disappeared, the interrupter will stay closed and the alloy in the thermal relay will gradually cool until all conditions are again normal. This condition will generally disappear if it was due to an insulator flashover, a swinging wire, or some other transient condition, in which event the circuit 102 suifers merely a thirty second interruption and then functions normally.

Tf, however, for any reason the condition causing the overload has not disappeared prior to the reclosing of the interrupter, as soon as the interrupter recloses the overload relay 110 again operates as soon as the interrupter recloses) dueto the overload and energizes the trip coil 105, causing the interrupter to open. The time limit relay 120 is then energized and after it has had time to operate, that is to say, in thirty seconds, the interrupter recloses. If the overload still persists, it again opens. This alternate opening and reclosing (after an interval of thirty seconds) would continue indefinitely were it not for the thermal relay which is set to limit the number of such reclosures. We can assume, for example, that it is set to allow siX reclosures and prevent a seventh.

The thermal relay prevents this seventh reclosure as follows. The interrupter having been reclosed the sixth time and having opened due to the persistence of the overload, the time limit relay 120 is energized but before it can close the circuit at the contacts 124 and thus cause a reclosure, the alloy 16 of the thermal relay melts or softens suiiiciently to allow the plunger 17 to drop. This closes a circuit through the fingers 23, a Wire 250, the coil 3l, a wire 251, the Wire 215, the arm 131., the wire 216, the wire 200, thebattery 140, the wire 206, and a wire 252. The coil 3l being energized, lifts the member 35 from the fingers 36.

In the form of my invention shown the coil 31 and certain associated parts act as a reset means. That is, as soon as the alloy 16'melts and cross bar 22 (with its connected parts) falls, the coil 31 is energized (through the lingers 23) and the moving element associated with the coil resets the cross bar 22. That is, the cross bar 22 is pushed up to its original position. Current is simultaneously cut 0H the wire 11 (at the fingers 36) and the alloy 16 also cools or resets.

The opening of the circuit at the fingers 36 opens the circuit through the wire 221 of the wire 11 of the thermal'relay, and the circuit through the wire 213 to the time element relay 120. The time limit relay 120 therefore does not complete its operation but drops baclr to its initial position so that the closing coil 104 cannot be energized and the interrupter stays open. The coil 31 of the thermal relay is, however, still energized and holds the plunger 17 `in its upper position where it is locked by the alloy 16 as the alloy cools. The parts will remain in this position until an operator discovers that the circuit is open.

The operator can then throw the manual control switch into the closing position so that the arm 131 contacts with the contact 134 and the closing coil 104 is energized through a wire 260, thus closing the interrupter. If the line has' been repaired, the overload will not recur and the interrupter stays closed. The operator then lets go of the manual switch, which snaps back to its central position in contact with the contact 133. With the breaker closed,'it can be manually tripped by throwing the arm 131 into contact with the contact 135, which energizes the trip coil through a wire 262 and the wire 203. If the arm 131 were allowed to return to its central position when released, the interrupter would automatically reclose and therefore it is desirable to provide means for locking the arm 131 in contact with the contact 135. In' most central stations some visible means is now provided for attachment to the manual switch locking it in the opening position to indicate that the interrupter has been deliberately opened and should not be 'closed unless the operator is sure that there vare no workmen-on the line fed by the 1nterrupter. This visible means will obviously number prevent automatic reclosure since it holds'the manual switch open. If such separate visible means is not` u'sed, it is preferable to soy construct the manual switch 130 that it will not snap back to its central position from the opening position when released by the operator.

It will be noted that in the form of my invention illustrated the reclosing of the circuit interrupter is finally terminated by opening a switch in the circuit of the closing coil. As will be readily understood by one skilled in the art, this termination can be accomplished by closing a switch which shunts the closing coil or by a latch or toggle which locks the mechanism of the interrupter. All such expedients, which I consider in view of the state ofthe art as mechanically equivalent to the switch used by me, are included in the general term inhibitor which should be understood to mean anything which inhibits or prevents movement of something else.

It' will be noted that by the use of the thermal relay/I provide a device which integrates abnormal conditions over a considerable time. By providing heat insulation l5 about the wire 1l, the rate of cooling of the alloy 16 may be made very slow. If, therefore, the interrupter opensunder overload one or more times and then stays closed for a considerable time, if the overload then recurs and the interrupter opens, the alloy may retain suiicient heat to cut down the of subsequent reclosures. The amount of heat so retained is (roughly) inversely proportional to the time that the interrupter has remained closed.

Suppose, for example, the interrupter has reclosed live times successively under an overload which then disappears. If the interrupter remains closed for say twenty-four hours, the allov` if a certain amount of heat insulation is provided, will have entirely cooled so that the interrupter will reclose six times before locking open. If, however, the interruptcr opens thirty minutes after it has been closed subsequent to five successive reclosures, the alloy will be suiiiciently hot to allow say three reclosures, 'and if it opens in fifteen minutes, it will allow only two reclosures. This is important since it is not desirable to allow repeated reclosures on a damaged line.

While I have shown a reclosing interrupter using a specific heat storage device in which I depend upon the melting of a body of metal to allow one member of the device to move from one position to another, it will be obvious to one skilled in the art that reclosing interrupters could be made using various other forms of heat storage devices such as those which depend merely upon expansion undefthe influence of heat, many well known forms of heat storage devices of the expansion type being available for this purpose.

I claim as my invention:

l. In an electrically energized device, the combination of: an lelectrically energized element; a switch for controlling the liow of electrical energy through said element; a heat storage device having a member which moves from a primary position to a secondary position whenever said heat storage device has received a definite amount of heat; an electricallydriven reset; means by which said reset operates said switch; `means by which said movement of the member in said heat storage device from said primary position to said secondary position actuates said reset; and means by which said reset when actuated by said means returns said member to its primary position.

2. In combination with an electric circuit system: a switch in said vsystem having separable contacts through which the electric current of said system passes; opening means for causing said contacts to open upon the occurrence of a predetermined condition in said system; closing means for causing said contacts to close; an inhibitor adapted to prevent said closing means from operating; a heat storage device having a moving element, said heatstorage device being so designed that said moving element moves from an inactive position to an active position whenever a definite quantity of heat has been delivered to said heat storage device; means for delivering heat to said heat storage device while said contacts are open; means by which said moving element when in its active position actuates said inhibitor to prevent said closing means from operating; a reset means actuated whenever said moving element reaches its active position; means by which the actuation of said reset means resets said element in its inactive po sition; and means for discontinuing the sup ply of heat to said heat storage means whenever said reset means operates.

3. In combination with an electric circuit' system: a switch in said system having separable contacts through which the electric' current of said system passes; opening means for causing said contacts to open upon the occurrenceof a predetermined condition in said system; closing means for causing said contacts to close; an inhibitor adapted to prevent said closing means from operating; a heat storage device having a moving element, said heat storage device being so designed that said moving element moves from an inactive position to an active position whenever a definite quantity of heat has been delivered to said heat storage device; means for delivering heat to said heat storage device while said contacts are open; means by which said moving element when in its 'active position actuates said inhibitor to prevent said clesmg means from operating; a reset means actuated 4whenever said moving element reaches its active position; means by which the actuation of said reset means resets said element in its inactive position; means for locking said reset means in its operated position; means by which an attendant operating the system can release said reset means from its locked position; and means for discontinuing the supply of heat to said heat storage means whenever said reset means operates.

4. In an electric circuit system having a switch with separable contacts through which the electric current of vsaid system passes, said switch having opening and. closing means, a control system comprising: a heat storage means adapted to receive heat when said separable contacts are separated and to prevent the reclosure ofthe switch after the heat storage means has received a definite increment of heat; a reset means actuated from said heat storage means after it has received a definite increment of heat;

.means by which said reset means prevents further heat from entering said heat stor'- f age means after said reset means is thrown into active position by saidl heat storage means; and means by which an attendant of the'system may cause said reset means to as! sume its inactive position.

5. In an electriccircuit system having a switch with separable contacts through which the electric current of said system passes, said switch having opening and closing means, a control system comprising: a he'at storage means adapted to receive heat when said separable contacts are separted and to prevent the reclosure ofthe switch after the heat storage means has received a definite increment of heat; a reset means actuated v from said heat storage means after it has received a definite increment of heat; means by which said reset means prevents further heat from entering said heat storage means after said reset means 1s thrownrlnto actlve posl- .tion by said heat storage means; means by which said reset means in passing from its inactive to its active position forces said heat l storage means into its inactive position; and

means by which an attendant of the system may cause said reset means to assume its inactive position.

6. In an electric circuit system having a switch vwith separable contacts through which the electric current of said `system passes, said switch having opening and closing means, a, cont-rolisystm comprising: a heat storage means adapted tol receiver heat when said separable contacts are separated and to prevent the reclosure of the switch after the heat stora e means has received a definite increment o heat; a reset means actuated from said heat storage means after it has received a definite increment of: heat;

means by which said reset means preventsl further heat from entering said heat storage means after said reset means is thrown into active position by said heat storage means; and a three-way switch so connected that in its normal position it enables said heat storage means to receive heat as above described, in its off position it disconnects said heat storage means and actuates the opening means, and in its closed position it disconnects said heat storage means and actuates the closing means.

Aa definite increment of-heat; a reset means s actuated from said heatstorage means after it has received a definite increment of heat; means by which saidreset means prevents further heat from entering said heat storage means after said reset means is thrown into active position by said heat storage means; means by which said reset means in passing from its inactive to its active position forces said heat storage means into its* inactive position; and a three-way switch so connected' that in its normal position it enables said heat storage means to receive heat as above described, in its off position it disconnects said heat storage means and actuates the opening means, and in its closed position 1t disconnects said heat storage -means and actuates the closing means.

8. In an electric circuit system having a switch with separable contacts through which the electric current of said system passes, said switch havingl opening and closing means, a control system comprising; a heat storage means adaptedto receive heat and to 'prevent 'the reclosure of the switch after the heat -storage means has receiveda definite increment of heat; a reset means ac,- tuated from said heat storage means after it has received a definite increment'of heat; means by which said reset means prevents Afurther heat from entering said heat storage means aftersaid reset'means is thrown into active position by saidl, heat storage means; and a three-way switch so connected that in its normal position it enables said heat stor.- age means to receive heat as above described, in its off position it disconnects said heat storage means and actuates the opening means, and in its closed position it discon nects said heat storage means and actuates the closing means, said reset means being released from the reset position whenever said three-Way switch is moved from its normal position. a

9. In an electric circuit system having a switch with separable contacts through which the electric current of said system passes, said switch having opening and closactive i sition by said heat storage means;

means yiwhich said reset means' in passlng from its inactive to its active position forces said heat storage means into its inactive position; and a three-way switch so connected that in its normal position it enables said heat storage means to receive heat as above described, in its ofi' position it disconnects said heat storage means and actuates the opening means, and in its closed position it disconnects said heat storage means and actuates the closing means, said reset means being released from the reset position whenever said three-way switch is moved from its normal position.

10. In combination with an electric circuit system; a switch in said system ,having separable contacts through which the electric current f said system passes; opening means for causing said contacts to open upon the occurrence of a predetermined condition in said system; closing means for causing said contacts A4to close; an inhibitor adapted to prevent said closing means from operating; a heat storage device having a moving element, said heat storage device being so designed that said moving element moves from an inactive position to an active position whenever a definite quantity of heat has been delivered to said leat storage device; means for de livering heatto said heat storage device while said contacts are open; a time limit relay adapted to actuate the closing means in a definite time after saidseparable contacts y have opened, unless prevented by the inhib- 1tor;.means by which said moving element When'in its active position actuates said inhibitorto prevent sald closing meansfrom operating; a reset `means actuated whenever said moving element 4reaches its active positlon; means .by which the actuation of said resetmeans resets said element in its inactive position; and means -for discontinuing the Y supply of heatto said heat storage means whenever said reset means operates.

current of said system passes; opening means for causing said contacts to open upon the ,occurrence of a predetermined condition in to said heat storage device; means for delivf ering heat to said heat storage device while said contacts are open; a time limitrelay adapted to actuate the closing means in a delinite time after said separable contacts have opened, unless prevented by the inhibitor; means, by which said moving element when in its active position actuates said inhibitor to prevent said closing means from operating; a reset means actuated whenever said moving element reaches its active position; means by which the actuation of said reset means resets said. element in its inactive hibitor to prevent said closing means from position; means for locking said reset.means in its operated position; means by which an attendant operating the system can release said reset means from its locked position; and

day of July, 1931.

i y FORD W. HARRIS'.

11. -In combination with an electric circuit system: a switch in said system having separable contacts through which the electric 

